select * from (select c.*, rownum rn from content c order by addtime) where rn >= 1 and rn <= 5.select * from (select rownum rn, t.* from (select title, addtime from content order by addtime desc) t) where rn >= 1 and rn <= 5.select * from (select rownum rn, t.* from (select title, addtime from content order by addtime desc) t where rownum <= 10) where rn >= 3.